Storytellers Gene Roddenberry, Irwin Allen and Rod Serling created the storylines and characters behind the best-loved futuristic television of their time. But as Roddenberry's "Star Trek" competed for ratings with Allen's "Lost in Space," each show's creator aimed for a very different direction. This episode explores how Roddenberry and Serling (of "The Twilight Zone") used the future as a stage for modern morality plays, and William Shatner, Leonard Nimoy, Nichelle Nichols and other science-fiction stars describe how they prepared to interact on-camera with a malevolent alien force ... or, perhaps, a giant radish.